Re: [PATCH] scripts/coccinelle/misc/shift.cocci: detect < or > that should be a shift

On Thu, 8 Feb 2018, Dan Carpenter wrote:

> On Thu, Feb 08, 2018 at 01:53:54PM +0100, Julia Lawall wrote:> > This checks for a comparison using < or > between two constants,> > considering both explicit constants (1, 2, etc) and macros defined> > with #define. False positives are possible in the latter case, when> > a macro may have multiple possible definitions and it is indeed> > necessary to check the value. There are currently two such false> > positives, in drivers/net/ethernet/chelsio/cxgb3/sge.c:> >> > q->fl[0].use_pages = FL0_PG_CHUNK_SIZE > 0;> > q->fl[1].use_pages = FL1_PG_CHUNK_SIZE > 0;> >>> We could eliminate both these false postives by ignoring >> vs >. Did> searching for > actually find any bugs? I think you were right that> right shifting a constant is way less common than left shifting and I> have some smatch scripts where I ignore right shifting bugs.>> On the other hand, two false positives are not a big deal.

I found no bugs with > at the moment. I figured that the person couldhave just as easily written 0 < FL0_PG_CHUNK_SIZE, so it was not worthmaking a special case. But if anyone wants me to drop the case id > cst,then I can do that.